Elucidation of mechanisms of the control gene expression is an important and rapidly growing area of research. A number of protein factors that directly affect the initiation of specific gene transcription in specific tissues have been isolated. It is the overall goal of this project to generate polyclonal and monoclonal antibodies against various DNA-binding transcriptional factors involved in the control of specific gene expression. In Phase I, we demonstrated the feasibility of our approach by developing antibodies against Pit-1, a transcription factor involved in the control of expression of the genes for prolactin and growth hormone. In Phase II, the effort will be expanded to include eight other DNA- binding transcription factors, as well as two enzymes in the cytoplasmic signal transduction cascade. Particular emphasis will be placed on generating antibodies specific for phosphorylated residues on each of the factors to produce antibodies capable of distinguishing phosphorylated and non-phosphorylated forms of each factor. Availability of such antibodies will have significant impact in furthering our understanding of the roles these molecules play in the control of differentiation and gene expression, and have a number of potential clinical applications as well.